Lesson 2: Dictionary's and 2 Dimensional Arrays

Advay Shindikar and Amay Advani

Objective:

Understand the concept of dictionaries and how they can be applied
Learn how to add, modify, and delete entries in a dictionary using the assignment operator and the del keyword
Understand the concept of 2D arrays and how they can be used to store data in rows and columns
Learn how to create a 2D array in Python using a nested list
Understand how to access values in a 2D array using row and column indices
Learn how to use indexing and slicing to access a subset of a 2D array

student = {'name': 'Advay', 'age': 16, 'Sophomore'}

students = ['advay', 'amay', 'rohin', 'alex', 'ethan']

Check In:

Of the above code segments, which is a list and which is a dictionary?
What is a dictionary and how is it used?
What is a 2D Array?
How are 2D Arrays different from 1D Arrays or Lists and what can they be used for?

Manipulating Dictionaries

grocery_dict = {}

# ask the user to enter grocery items and their prices
while True:
    item = input("Enter an item for your grocery list (or 'done' to exit): ")
    if item == "done":
        break
    else:
        price = float(input("Enter the price of {}: ".format(item)))
        grocery_dict[item] = price

# print the grocery list and total cost
total_cost = 0
while True:
    print("Your grocery list:")
    for item, price in grocery_dict.items():
        print("- {}: ${}".format(item, price))
    print("Total cost: ${}".format(total_cost))
    
    # ask the user to choose an action
    action = input("What would you like to do? (add/remove/done) ")
    
    # add a new item to the grocery list
    if action == "add":
        item = input("Enter the name of the item you would like to add: ")
        price = float(input("Enter the price of {}: ".format(item)))
        grocery_dict[item] = price
        total_cost += price
    
    # remove an item from the           j
        item = input("Enter the name of the item you would like to remove: ")
        if item in grocery_dict:
            total_cost -= grocery_dict[item]
            del grocery_dict[item]
        else:
            print("Item not found in grocery list!")
    
    # exit the loop and print the final grocery list and total cost
    elif action == "done":
        break

print("Final grocery list:")
for item, price in grocery_dict.items():
    print("- {}: ${}".format(item, price))
print("Total cost: ${}".format(total_cost))